This invention relates to a tracer control method and, more particularly, to a tracer control method whereby any tracing pattern can be simply created and tracer machining performed in accordance with the tracing pattern.
A tracer apparatus operates by causing a tracer head to trace a model, calculating velocity commands along various axes by means of a tracer arithmetic circuit using a deflection value sensed by the tracer head. The tracer apparatus controls driving motors for the corresponding axes on the basis of the velocity commands along these axes to transport a tool relative to a workpiece, and repeats these operations to machine the workpiece into a shape identical with that of the model. The tracing methods (tracing patterns) that are available with the foregoing tracer apparatus are (a) manual tracing, (b) two-way scan tracing, (c) one-way scan tracing, (d) 360.degree. contour tracing, (e) partial contour tracing and (f) three-dimensional tracing. The conventional practice is to specify one of the tracing methods (a) through (f), enter tracer machining conditions, such as tracing velocity, reference deflection value, tracing direction, pick-feed value and pick-feed direction, as well as the tracing area, and trace the specified pattern on the basis of these data. FIGS. 1(A), 1(B) and 1(C) show examples of two-way scan tracing, one-way scan tracing and 360.degree. contour tracing, respectively. The tracing pattern for two-way scan tracing is specified by a combination of approach motion S1, tracing motion S2 in one direction, pick-feed motion S3, tracing motion S4 in the return direction, and pick-feed motion S5. The tracing pattern for one-way scan tracing is specified by a combination of approach motion S1, tracing motion S2, rapid-return motion S3 along the +Z axis, return motion S4 in a direction opposite to tracing feed, rapid approach motion S5, and pick-feed motion S6. The tracing pattern for 360.degree. contour tracing is specified by a combination of approach motion S1, contour tracing motion S2, and pick-feed motion S3.
Certain users have recently come to require tracer control based on patterns other than the tracing patterns (a) through (f) described above. For example, as shown in FIG. 2, there is a requirement for a tracer control method for repeating tracing in accordance with a rectangular tracing pattern comprising scan tracing motion along the +X axis, scan tracing motion S2 along the -Y axis, scan tracing motion S3 along the -X axis, and scan tracing motion S4 along the +Y axis. In cases such as the above-mentioned, the manufacturer is required on each occasion to redesign, or to modify the software of, the tracer apparatus so that tracer control conforming to the tracing pattern required by each user can be implemented. However, offering a tracer apparatus for each and every tracing pattern is a burden for the manufacturer. The user also is inconvenienced in that a single tracer apparatus cannot be made to perform tracing tailored to the user's own tracing patterns.